Q&A: How the global minimum tax would work

In today's economy, multinationals can earn big profits from things like trademarks and intellectual property that are easier than factories to move. Companies can assign the earnings they generate to a subsidiary in a country where tax rates are very low.

Some countries compete for revenue by using rock-bottom rates to lure companies, attracting huge tax bases that generate large revenue even with tax rates only marginally above zero.

The basic idea is simple: Countries would legislate a minimum rate of at least 15% for very big companies with annual revenues over 750 million euros ($864 million)

If company earnings go untaxed or lightly taxed in one of the world's tax havens, their home country would impose a top-up tax that would bring the rate to 15%.

Biden has staked a claim that the U.S. must join the global minimum tax in order to persuade other nations to do so. That would involve raising the current rate for foreign earnings from 10.5% to reflect the global minimum. His tax proposals are still being negotiated in Congress.

U.S. participation in the minimum tax deal is crucial, simply because so many multinationals are headquartered there — 28% of the 2,000 biggest global companies. Complete rejection of Biden's global minimum proposal would seriously undermine the international deal.

Some developing countries and advocacy groups such as Oxfam and the UK-based Tax Justice Network say the 15% rate is too low.

And although the global minimum would capture some $150 billion in new revenue for governments, most of it would go to rich countries because they are where many of the biggest multinationals are headquartered. Developing countries took part in the talks and all signed except for Nigeria, Kenya, Pakistan and Sri Lanka.

The EU Tax Observatory research consortium cautions that exemptions for companies with actual assets and employees in a given country could "exacerbate tax competition by giving firms incentives to move real activity to tax havens."

That means some tax competition among countries would still be possible when actual business operations — as opposed to shifty accounting — are involved.

Backing from the G-20 leaders completes a yearslong process of negotiation. Once approval is reflected in the summit's final statement, expected Sunday, implementation then moves to the individual nations.

The tax on earnings where companies have no physical presence would require countries to sign on to an intergovernmental agreement in 2022, with implementation in 2023.

The plan would also let countries tax part of the earnings of the 100 or so biggest multinationals when they do business in places where they have no physical presence, such as through internet retailing or advertising. The tax would only apply to a portion of profits above a profit margin of 10%.

In return, other countries would abolish their unilateral digital services taxes on U.S. tech giants such as Google, Facebook and Amazon.